One Word_Microbiology Flashcards
ADP ribosylating A-B toxins - Bordetella pertussis
Increases cAMP by inhibiting Gαi; causes whooping cough; inhibits chemokine receptor, causing lymphocytosis
ADP ribosylating A-B toxins - Corynebacterium diphtheriae
Inactivates elongation factor (EF-2) (similar to Pseudomonas exotoxin A); causes pharyngitis and “pseugomembrane” in throat
ADP ribosylating A-B toxins - E. coli
Heat-labile toxin stimulates adenylate cyclase. Heat-stable toxin stimulates guanylate cyclase. Both cause watery diarrhea.
ADP ribosylating A-B toxins - Vibrio cholerae
ADP ribosylation of G protein stimulates adenylyl cyclase; ↑ pumping of Cl- into gut and ↓ Na+ absorption. H2O moves into gut lumen; causes voluminous rice-water diarrhea
Bacterial structures - Capsule
Function - Protects against phagocytosis Chemical composition - Polysaccharide (except Bacillus anthracis, which contains D-glutamate)
Bacterial structures - Cell wall/cell membrane (gram positives)
Function - Major surface antigen Chemical composition - Peptidoglycan for support. Teichoic acid induces TNF and IL-1
Bacterial structures - Flagellum
Function - Motility Chemical composition - Protein
Bacterial structures - Glycocalyx
Function - Mediates adherence to surfaces, especially foreign surfaces (e.g., indwelling catheters) Chemical composition - Polysaccharide
Bacterial structures - Outer membrane (gram negatives)
Function - Site of endotoxin (lipopolysaccharide); major surface antigen Chemical composition - Lipid A induces TNF and IL-1; polysaccharide is the antigen
Bacterial structures - Peptidoglycan
Function - Gives rigid support, protects against osmotic pressure Chemical composition - Sugar backbone with cross-linked peptide side chains
Bacterial structures - Periplasm
Function - Space between the cytoplasmic membrane and peptidoglycan wall in gram-negative bacteria Chemical composition - Contains many hydrolytic enzymes, including β-lactamases
Bacterial structures - Pilus/fimbria
Function - Mediate adherence of bacteria to cell surface; sex pilus forms attachment between 2 bacteria during conjugation Chemical composition - Glycoprotein
Bacterial structures - Plasma membrane
Function - Site of oxidative and transport enzymes Chemical composition - Lipoprotein bilayer
Bacterial structures - Plasmid
Function - Contains a variety of genes for antibiotic resistance, enzymes, and toxins Chemical composition - DNA
Bacterial structures - Ribosome
Function - Protein synthesis Chemical composition - 50S and 30S subunits
Bacterial structures - Spore
Function - Provides resistance to dehydration, heat, and chemicals Chemical composition - Keratin-like coat, dipicolinic acid.
Bacterial virulence factors - IgA protease
Enzyme that cleaves IgA. Secreted by S. pneumoniae, H. Influenzae type B, and Neisseria (SHiN) in order to colonize respiratory mucosa
Bacterial virulence factors - M protein (group A streptococcus)
Helps prevent phagocytosis
Bacterial virulence factors - Protein A (S. aureus)
Binds Fc region of Ig. Prevents opsonization and phagocytosis.
Lysogeny, specialized transduction
①Shiga-like toxin ②Botulinum toxin ③Cholera toxin ④Diphtheria toxin ⑤Erythrogenic toxin of Streptococcus pyogenes
Other toxins - Bacillus anthracis
Edema factor, part of the toxin complex, is an adenylate cyclase
Other toxins - C. botulinum
Blocks the release of acetylcholine; causes anticholinergic symptoms, CNS paralysis, especially cranial nerves; spores found in canned food, honey (causes floppy baby)
Other toxins - C. tetani
Blocks the release of inhibitory neurotransmitters GABA and glycine; causes “lockjaw”
Other toxins - Clostridium perfringens
α toxin, a lecithinase that acts as a phospholipase to cleave cell membranes and causes gas gangrene; get double zone of hemolysis on blood agar
Other toxins - S. pyogenes
Streptolysin O is a hemolysin; antigen for ASO antibody, which is used in the diagnosis of rheumatic fever
Other toxins - Shigella
Shiga toxin (also produced by E. coli O157:H7) cleaves host cell rRNA (inactivates 60S ribosome); also enhances cytokine release, causing HUS
Parasite hints - B12 deficiency
Diphyllobothrium latum
Parasite hints - Biliary tract disease, cholangiocarcinoma
Clonorchis sinensis
Parasite hints - Brain cysts, seizures
Taenia solium (cysticercosis)
Parasite hints - Hematuria, bladder cancer
Schistosoma haematobium
Parasite hints - Hemoptysis
Paragonimus westermani
Parasite hints - Liver cysts
Echinococcus granulosus
Parasite hints - Microcytic anemia
Ancylostoma, Necator
Parasite hints - Perianal pruritus
Enterobius
Parasite hints - Portal hypertension
Schistosoma mansoni
Superantigens - S. aureus
TSST-1 superantigen causes toxic shock syndrome (fever, rash, shock). Other S. aureus toxins include enterotoxins that cause food poisoning as well as exfoliatin, which causes staphylococcal scalded skin syndrome.
Superantigens - S. pyogenes
Scarlet fever-erythrogenic toxin causes toxic shock-like syndrome
Unusual cell membranes/walls - Chlamydiae
Cell wall lacks muramic acid
Unusual cell membranes/walls - Mycobacteria
Contain mycolic acid. High lipid content
Unusual cell membranes/walls - Mycoplasma
Contain sterols and have no cell wall
